In surgery, screws or other components often have to be tightened with a defined torque. In such cases, a maximum torque in the direction of the tightening of the screw must not be exceeded in order to avoid damage to the components or to bones. On the other hand, loosening of the screw should be possible, including with a higher torque, in order for it to be possible in the event of a seized screw to remove it again from the body. For this reason, torque limiters such as are used in surgery are fundamentally different from torque limiters such as are used generally in mechanics, since in the case of the latter a freewheel is usually arranged in the opposite direction.
There are torque limiters known from the prior art that operate with an elastic body which can transmit a torque from an inner shaft to an outer rotor. For instance, European Patent Application EP 2 085 041 A1 relates to a corresponding surgical instrument. It is disadvantageous, however, that the maximum torque is determined by the elastic body. Furthermore, fatigue of the synthetic materials of the elastic body may bring about a change in the properties of the instrument. This is disadvantageous, since the maximum transmissible torque can change.